David Lloyd Leisure has been ordered to pay £350,000 after pleading guilty to an incident where a five-year-old boy almost drowned.

The fitness firm alerted Hounslow Council’s health and safety officers of the incident at its Heston branch, Southall, in February 2013, after Blakeney Dear was found ‘bobbing’ up and down in the pool at a ‘kids holiday active’ session.

Blakeney, a non-swimmer, was allowed to take part in the half-term activity without armbands, which went against the club’s rules for non-swimmers or ‘poor’ swimmers.

Blakeney told staff that he could not swim but despite this he was not constantly supervised during the two-day swimming activity.

On the second day of his session, staff failed to support Blakeney in the water and he lost his ability to keep himself afloat with any floatation aid.

Another child taking part in the activity found Blakeney underwater. The child was asked by the lifeguard to go over and tell Blakeney to stop ‘bobbing’ up and down in the pool.

It is estimated that Blakeney was underwater for approximately five minutes before being pulled out and given CPR by the club’s lifeguard. He was also given CPR by paramedics when they arrived at the scene.

Blakeney was kept under observation in hospital for two nights but sustained no lasting injuries.

The council’s investigation found a series of failures that led to the incident.

Staff on the first day, who were told that Blakeney could not swim, failed to act when they realised he had no armbands and none were available at the club. This information was not passed to the family active co-ordinator. As a result, staff working on day two were also unaware of Blakeney’s inability to swim before the activity started.

When one of the team members became aware, after he told her, Blakeney was still allowed by staff to stay in the pool.

A team member in the pool told Blakeney and two other non-swimmers to come to her if they needed a woggle - a type of floatation aid.

Blakeney had a floatation aid at one point and was seen holding onto the poolside wall but eventually lost his ability to stay above the surface of the water and drifted from the poolside.

The team member in the pool failed to constantly supervise Blakeney for most of the time he was in the pool, leaving him without any support.

David Lloyd Leisure was charged with an offence under the Health and Safety at Work Act for failing to take all reasonably practicable measures for Blakeney’s safety during the swimming sessions.

At Isleworth Crown court the company was fined £330,000, ordered to pay £22,131.75 in court costs and a victim surcharge of £120.

Councillor Sue Sampson, cabinet member for community protection at Hounslow Council, said: “This serious incident could have resulted in a fatality. Thankfully the child involved has suffered no lasting consequences.

“The situation could have been avoided if the club had ensured that staff given the role of running and supervising the swimming activity, and parents enrolling their children to take part, were made aware that children should either be competent swimmers or needed to wear armbands at all times.”

A David Lloyd Leisure spokeswoman said: “The safety and security of our members is our number one priority, and we would like to express our deepest and most sincere apologies to Blakeney and his family for the distress caused.

"It was an unacceptable breach of our child safety policies and we want to reassure everyone that we have taken stringent measures to ensure that it doesn’t happen again.

“Following our investigation, we have extensively reviewed our safety policies to ensure the wellbeing of children in our clubs continues to be safe-guarded at all times.

“Those policies are embedded into the training that all team members working with children undergo, and we take firm and immediate action if any of the processes are not adhered to.

“We can confirm that the team members supervising the session are no longer with the business.”